Question

What factors influence an enzyme’s substrate specificity?

Short answer

The factors influencing an enzyme's substrate specificity are stereospecificity and geometric specificity.

Step-by-step solution

Enzyme’s substrate specificity

An enzyme's substrate specificity is a property that enables the enzyme to bind only to the specific substrate. Both enzymes and substrates have complementary sites for binding, which is explained through the "lock and key" model of enzyme function.

Factors that influence an enzyme’s substrate specificity.

The factors affecting the enzyme's substrate specificity are mentioned below:

1. Stereospecificity: Enzymes are very particular in binding and catalyzing the substrates and their reactions. Stereospecificity occurs because of inherent chirality. For instance, in the citric acid cycle, the enzyme aconitase catalyzes the interconversion of citrate and isocitrate.
2. Geometric specificity: Enzymes vary considerably in their degree of geometric specificity. A few enzymes are absolutely specific for only one compound. Most enzymes, however, catalyze the reactions of a small range of related compounds although with different efficiencies. For example, alcohol dehydrogenase catalyzes the oxidation of ethanol to acetaldehyde faster than it oxidizes other reactions.

Hence, stereospecificity and geometric specificity affect an enzyme's substrate specificity.